</varlistentry>

<varlistentry>

<term><option>-P <replaceable class="parameter">parallel_degree</replaceable></option></term>

<term><option>--parallel=<replaceable class="parameter">parallel_degree</replaceable></option></term>

<term><option>-P <replaceable class="parameter">parallel_workers</replaceable></option></term>

<term><option>--parallel=<replaceable class="parameter">parallel_workers</replaceable></option></term>

<listitem>

<para>

Specify the paralleldegree of <firstterm>parallel vacuum</firstterm>.

Specify thenumber ofparallelworkers for <firstterm>parallel vacuum</firstterm>.

This allows the vacuum to leverage multiple CPUs to process indexes.

See <xref linkend="sql-vacuum"/>.

</para>

if (nworkers<0||nworkers>MAX_PARALLEL_WORKER_LIMIT)

ereport(ERROR,

(errcode(ERRCODE_SYNTAX_ERROR),

errmsg("parallelvacuum degree must be between 0 and %d",

errmsg("parallelworkers for vacuum must be between 0 and %d",

MAX_PARALLEL_WORKER_LIMIT),

parser_errposition(pstate,opt->location)));

vacopts.parallel_workers=atoi(optarg);

if (vacopts.parallel_workers<0)

{

pg_log_error("parallelvacuum degreemust bea non-negative integer");

pg_log_error("parallelworkers for vacuummust begreater than or equal to zero");

exit(1);

}

break;

printf(_(" --no-index-cleanup don't remove index entries that point to dead tuples\n"));

printf(_(" --no-process-toast skip the TOAST table associated with the table to vacuum\n"));

printf(_(" --no-truncate don't truncate empty pages at the end of the table\n"));

printf(_(" -P, --parallel=PARALLEL_DEGREE use this many background workers for vacuum, if available\n"));

printf(_(" -P, --parallel=PARALLEL_WORKERS use this many background workers for vacuum, if available\n"));

printf(_(" -q, --quiet don't write any messages\n"));

printf(_(" --skip-locked skip relations that cannot be immediately locked\n"));

printf(_(" -t, --table='TABLE[(COLUMNS)]' vacuum specific table(s) only\n"));

UPDATE pvactst SET i = i WHERE i < 1000;

VACUUM (PARALLEL 0) pvactst; -- disable parallel vacuum

VACUUM (PARALLEL -1) pvactst; -- error

ERROR: parallelvacuum degree must be between 0 and 1024

ERROR: parallelworkers for vacuum must be between 0 and 1024

LINE 1: VACUUM (PARALLEL -1) pvactst;

^

VACUUM (PARALLEL 2, INDEX_CLEANUP FALSE) pvactst;